Lixiviación de concentrados de cobre con alto contenido de arsénico en medio cloro-cloruro

Revista de Metalurgia (Impact Factor: 0.29). 04/2003; 39(2). DOI: 10.3989/revmetalm.2003.v39.i2.319
Source: DOAJ


This work reports the results of copper concentrates leaching, which have high arsenic contents (up to 2.5 %). The treatments were carried out using chlorine that forms from sodium hypochlorite and sulphuric acid. The aim of this work is to obtain a solution having high copper content 4 to 6 g/1 and 5 to 7 g/1 free acid in order to submit it directly to a solvent extraction stage. In addition, this solution should have minimum content of arsenic and chloride ions. To carry out this investigation, an acrylic reactor was constructed where the leaching tests were made at constant temperature in a thermostatic bath under atmospheric pressure. The concentrate samples were obtained from mineral processing plants from Antofagasta, Chile. Typical variables were studied, such as leaching agent concentration, leaching time, pulp density and temperature among others. Some of the residues were analyzed by XRD and EPS. On the other hand, the solutions were analyzed by Atomic Absorption Spectroscopy. The results indicate solutions having the contents stated above can be obtained.Se ha estudiado la lixiviación de concentrados de cobre con alto contenido de arsénico (hasta 2,5 %), mediante un proceso de oxidación con cloro formado "in situ", por la reacción entre hipoclorito de sodio y ácido sulfúrico. El objetivo de estas experiencias es producir una solución de lixiviación, de características adecuadas para entrar a la etapa posterior de extracción por solventes (SX), es decir, entre 4 a 6 g/1 de cobre y 5 a 7 g/1 de ácido residual. Esta disolución, además, deberá contener cantidades mínimas de arsénico y cloruro. Las lixiviaciones se realizaron por agitación en un reactor de acrílico diseñado para tal efecto, a temperatura ambiente y a presión atmosférica. Se utilizaron concentrados de cobre de explotaciones mineras de Antofagasta (Chile). Se estudiaron algunas variables típicas de la lixiviación, como son: la concentración de agente lixiviante, el tiempo de lixiviación, el porcentaje de sólidos y la temperatura. La caracterización de algunos residuos sólidos, producto de las lixiviaciones, se realizó por DRX (Difracción de Rayos X) y EDS (Barrido de Energía Dispersiva de Rayos X). El cobre y arsénico en las disoluciones se analizaron mediante Espectroscopia de Absorción Atómica. Los resultados experimentales indican que es posible obtener soluciones de las características deseadas con este procedimiento, que utiliza reactivos comunes y de relativo bajo costo.

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    ABSTRACT: Copper is often associated with arsenic in mixed sulphide minerals such as enargite (Cu3AsS4) and tennantite (Cu12As4S13). Enargite, in particular, is the principal mineral in many deep epithermal copper–gold deposits. Most mining companies avoid exploiting such resources, because the arsenic can become a serious environmental liability or may considerably reduce the resource value due to hefty treatment charges. The few enargite deposits that have been exploited so far are usually rich in gold and silver. The first challenge in the exploitation of copper–arsenic sulphides is the effective separation of arsenic phases from other valuable minerals. In the last decade, though, it was shown that this is possible by pulp-potential adjustment (oxidative conditions) combined with pH adjustments (basic conditions) prior to flotation. In this way, two types of concentrate can be produced: one rich in arsenic and another low in arsenic but rich in other valuable metals. Arsenic-rich concentrates have traditionally been processed pyrometallurgically by reduction roasting to gaseous arsenic sulphide, which is then converted to arsenic trioxide. New pyrometallurgical technologies for the treatment of copper–arsenic sulphides include sulphidization roasting, sulphidization roasting and halogenation, and carbothermic reduction to copper arsenide. The hydrometallurgical treatment of copper–arsenic-antimony resources has been done by atmospheric leaching in alkaline sodium-sulphide solutions. Ultrafine grinding and ferric oxidation at atmospheric pressure, total pressure oxidation at temperatures above 220°C, and bacterial leaching have recently been tried on copper–arsenic sulphides, some with considerable success.
    No preview · Article · May 2007 · Mineral Processing and Extractive Metallurgy Review